Refactoring: Refactorings/Hide Delegate

A client calls a method on a delegate rather than using the public interface on the "server" class: The client knows too much about the inner workings of a delegate class.

Mechanics

1. For each method on the delegate, create a simple delegating method on the server
2. Adjust the client to call the server method
3. Test after adjusting each method
4. If no client needs to access the delegate anymore, remove the server's accessor for the delegate.
5. Test

Example

Before

class Person
  attr_accessor :manager

  # ...
end

class Department
  attr_reader :manager

  def initialize(manager)
    @manager = manager
  end
end

# client code
manager = john.department.manager

After

class Person
  extend Forwardable

  def_delegator :@department, :manager

  attr_accessor :manager

  def manager
    @department.manager
  end
end

class Department
  attr_reader :manager

  def initialize(manager)
    @manager = manager
  end
end

# client code
manager = john.manager